Itchy is wrong.
I copied this from another poster. Actually he is responding to another one of your posts? Why are you posting the same question on two different forums? Hmmm... anyhow Gord is correct.

gord wrote:

A work visa requires a sponsor. So when one first gets a work visa, the school has sponsored them. In exchange, the school dictates where the teacher can work. Same in in any country when one gets a sponsored work visa.

A letter of release is for Immigration that states the school will be removing their sponsorship of the visa. Once removed, the work visa holder has 14 days in which to find someone new to sponsor the work visa. Failing that, the visa expires and the person must leave the country.

Further, Immigration will not issue an additional work visa until the current work visa would have expired without a letter of release. Even if the original work visa was cancelled the day one received it, another will not be issued until that one would have expired without a letter of release.

One can take steps to try and ensure a school signs a letter of release, but to say one just has to leave the country to qualify for a new work visa is false information

All the info in correct, however, each immigration does what it wants. No set rules. One can leave anytime they want, immigration will not prevent you from leaving UNLESS you are on internation hold or broke some korean law and the man is looking for you. I do know this, if you split korea, immigration can bar you from re entering and if the school you're running from wants, they can "ask" immigration to bar you from korea. It all depends on "who you know" at immigration to ask for favors. Piss off a school and that school just may have enough power to bar you. But, if one is leaving korea because of a bad school, etc., why would they want to return?!? Chances are that the next school will also be a nightmare!